The present invention relates to an air bag system for a vehicle seat and, more particularly, an air bag system for a vehicle seat capable of absorbing an impact load applied from a side plate of a vehicle body to a passenger to protect the passenger from the impact load by forward spreading out an air bag provided in one side portion of a seat back when a vehicle collides in a side crash.
In order to avoid the direct impact between the side plate of the vehicle body such as a door plate deformed by the impact load and the passenger sat on the seat when the vehicle crashes at its side, various air bag systems have been proposed in the prior art, as has been known in Patent Application Publication (KOKAI) 4-50052, for example.
In a common configuration of this kind of the air bag system, an inflator and an air bag are installed together in a metal case. The air bag system is fitted to a side bracket which is secured to an outside of a seat back frame in the vehicle width direction. When the vehicle crash happened, the high pressure gas is immediately generated from the inflator and then injected into the air bag, so that the air bag can rapidly spread out forward from an opening portion of the metal case. At that time, the air bag is able to break through the stitching portion of the seat back cover to thus protrude into a compartment in a moment. A spreading direction of the air bag can be regulated by the opening portion of the metal case.
Fitting bolts are provided on the back surface of the inflator so as to protrude backward. The fitting bolts penetrate the rear surface portion of the metal case and fixed by the nuts. Why the inflator is secured on the rear surface portion of the metal case is due to receive and absorb the rearward reaction force which is developed by an expanding of the air bag.